Automated fiber placement mandrel joint configuration

Abstract

The present invention provides an automated fiber joint placement machine mandrel configuration where the lap joint is preferably parallel to the mold surface. Accordingly, the user may shim the mandrel segments without otherwise affecting the integrity of the seal. A lap joint is preferably utilized wherein mandrel segments are split at the stringer centerline through the middle of the hat or through the cap of the stringer. The lap joint is preferably designed such that the face sheets of the mandrel segments preferably lie flat on top of one another when placed in contact. The seal plane is thus protected.

Description

TECHNICAL FIELD[0001]This invention relates generally to joint configurations and specifically to automated fiber placement machine mandrel joint configurations.BACKGROUND OF THE INVENTION[0002]Stringers are used quite often in the aerospace industry. A stringer is a structural member used in fuselage structures. Stringers are generally straight, long, narrow components of the structural skeleton of an aircraft which are joined to the skin of an aircraft to strengthen and stiffen, thus providing support and definition to the skin of the structure. Accordingly, stringers are preferably mounted to the interior portion of the skin of the aircraft in order to reinforce the skin. Stringers typically include an upward oriented crown structure, sometimes referred to as a hat or cap, and a pair of opposite side surfaces, all of which extend along the entire length of the stringer. The hat is preferably what is mounted and abuts the skin of an aircraft.[0003]In the past, mandrel segments hav...

AI Technical Summary

Benefits of technology

[0007]Another embodiment of the present invention provides a lap joint assembly including a first mandrel face sheet and a second mandrel face sheet wherein the second mandrel face sheet is preferably aligned to form a lap joint with the first mandrel face sheet. A seal plane is preferably embedded between the first mandrel face sheet and the second mandrel face sheet. Further embodiments preferably provide that the mandrel comprised of the first mandrel face sheet and the second mandrel face sheet is split at a stringer centerline through a cap of the stringer. Accordingly, the placement of the split at the stringer centerline minimizes mark-off impact. In other embodiments, the configuration of the lap joint provides a gap between mandrel segments forming a mandrel, whereby tolerances are achieved without affecting the seal plane. The lap joint is preferably positioned parallel to a mold surface, and the first mandrel face sheet and second mandrel face sheet lie flat against each other protecting the seal plane embedded between the face sheets.

Problems solved by technology

If there is a mismatch in the mandrel segments and mark-off or a wrinkle occurs, it may cause fiber distortion which results in a weaker laminate.

This is particularly problematic when the split occurs between the stringers because when such distortion or mark-off occurs, it is hard to replace or repair the stringers because of the positioning of the split.

When these joints are utilized, there is a potential for leakage which can result in defects in the laminate and possible transfer of abnormalities to the resultant part.

Butt joint positioning also is problematic in that mandrel face sheets are aligned at an angle, causing a wiping effect to occur in the seal being formed.

The seal begins to roll or slide, and thus, the seal is worn down and becomes less advantageous for the production process.

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